This invention relates to ladders, scaffolds, and similar equipment, and in particular is directed to ladder extenders or levelers which may be attached or affixed to the ladder rails of an extension ladder. The invention is more specifically concerned with devices that permit the base of the ladder to be adjusted to match the terrain so as to permit the ladder to be erected plumb, that is, not leaning to the left or right if the ground support is uneven.
Currently, where ladders are used in outdoor work, i.e., construction, carpentry, maintenance, or painting, the worker depends on the base of the ladder being more-or-less level so that the two rails of the ladder will be supported at the same level. However, it is seldom the case that the ground next to a structure is level, even where the ground is paved. The two rails are typically about sixteen inches apart, while the ladder may extend vertically for twenty-eight feet or more. If there is a difference in grade between the left and right side of the ladder of only one-half inch, this means that at an elevation of sixteen feet, the ladder is leaning six inches to the left or right, and at twenty-eight feet, this lean can be ten inches. With this much lean, the workman is placed in a dangerous position. In order to straighten the ladder, it is usual to place a prop under the base of one or the other ladder rails, i.e., a board or a slab. However, this is also considered an unsafe practice, as the ladder, board, or slab may be prone to slippage. Also, it is difficult to find a board or slab of the correct thickness and which is also strong enough to support the weight of the ladder plus the worker and any equipment.
While a number of braces have been proposed to hold up the upper end of the ladder, there has not been an adequate adjustment device for lengthening one or the other of the ladder rails at the lower end or base in order to accommodate uneven ground.
Accordingly, it is an object of the present invention to provide a ladder leveling arrangement that avoids the drawbacks of the prior art.
It is another object to provide a ladder leveling arrangement that attaches unobtrusively to the base of the ladder and permits the base or feet of the ladder rails to be extended so that the ladder is plumb when it is erected.
It is a more specific object to provide a pair of simple and straightforward extenders of a sleeve and slide-leg configuration that permit the ladder to be used on uneven ground, sloping ground, or even on steps or stairs.
In accordance with one aspect of the present invention, a ladder leveling arrangement is provided for adjusting the base of a ladder so that it may be erected plumb on uneven ground. A left tubular sleeve and a right tubular sleeve attach onto lower ends of the left and right vertical ladder rails, each of the tubular sleeves defining a vertical passage within it. Slidably fitted within the passage of these tubular sleeves are a left slide leg and a right slide leg. There are suitable means provided for attaching the left and right tubular sleeves onto the lower ends of the ladder rails, and means for setting the positions of the slide legs with respect to the associated tubular sleeves.
In one preferred embodiment, the tubular sleeve and the slide leg within it are in the form of C-channel members of generally square or rectangular cross section. The sleeves have openings on the webs for attaching to the ladder. In the case of most aluminum and fiberglass ladders, the rungs are hollow, tubular members with a bore that extends through the ladder rails. In such case, a threaded rod can run through the lowest rung, and through the openings in the sleeve members. Washers and threaded nuts hold the sleeve in place on the rail. Another opening, i.e., bolt hole, exists at the bottom of the rail, where the usual ladder footing is attached. This footing is removed and is installed instead on the lower end of the slide leg. There is an opening in the web of the sleeve near the lower end, and the sleeve is also secured here to the rail by means of a bolt, washer and nut passing through this opening and the bolt hole at the lower end of the ladder rail.
The tubular sleeves each have at least one pin opening through them, and preferably there are three of these near the upper end. A row of pin openings also along at least the upper half of the slide leg. These openings align with one another as the slide leg is adjusted. A retaining pin then passes through the aligned holes or pin openings to lock the slide leg in position in respect to the associated tubular mounting sleeve. Because the two slide legs can be adjusted independently over a length of twelve inches or more, it is possible to adjust these so the ladder may be used on sloping or rocky terrain, or even on stairs or steps where the two ladder rails are on different stair treads.
This construction of a ladder extender or leveler device does not interfere with the operation of the upper or extension portion of the ladder, which typically has to slide along the inner sides of the main portion ladder rails.
In the case of a wooden ladder, it is possible to secure the tubular sleeves to the ladder rails with a set of wood screws. It is also possible to secure these sleeves to an aluminum or other ladder by drilling suitable holes in the ladder rails. In that case, the holes may be threaded for receiving screws. It is also possible to use straps, clamps, or other fastening members to mount the sleeve members onto the lower ends of the ladder rails.
In the preferred embodiment, the sleeve and slide legs are C-channel members of generally rectangular section. However, these may be constructed of members of other shape, such as square tubular members. In that case, countersunk holes may be drilled into the outer sleeve so that fastening members do not interfere with sliding of the slide legs. In other embodiments, the slide legs may be I-beam members, or may be solid.
The term xe2x80x9cverticalxe2x80x9d as used here means in the longitudinal direction in respect to the ladder rails, i.e., parallel to the ladder rails.
The above and many other objects, features, and advantages of this invention will be more fully appreciated from the ensuing description of a preferred embodiment, which is to be read in conjunction with the accompanying Drawing.